The Clinical and Diagnostic Trials Section provides full statistical support for the Brain Tumor Cooperative Group (BTCG), a multicenter group of neurosurgeons, neuro-oncologists, radiotherapists, neuro-radiologists, and neuro-pathologists conducting randomized trials for patients with primary brain tumors (with emphasis on malignant gliomas). During this past year, the BTCG completed the accrual of patients to a randomized Phase III trial, BTCG 87-01, investigating interstitial radiation (seed implants) as an addition to the customary external beam radiation and chemotherapy. Preliminary analyses of the data have been performed and the results presented. Patients randomized to interstitial radiation had increased survival compared to the standard arm; this difference was statistically significant in both the Randomized Population and the Valid Study Group. As with past studies, age, Karnofsky performance status, and histopathology were found to be significant prognostic factors. Models adjusting for the three prognostic factors suggested that the treatment difference in favor of interstitial radiation occurred for Glioblastoma Multiforme but not for the other malignant gliomas. (However, this latter subgroup had small numbers and differences were not statistically significant.) Pathology review at time of surgery following possible ~failure~ showed that categorization by viable tumor versus necrosis (with or without tumor cells) was significantly predictive of subsequent survival. During this year, accrual was completed on another randomized trial, BTCG 89-01, that compares two Phase III chemotherapy regimens to be given in addition to surgery and radiotherapy. One regimen is the standard intravenous BCNU; the second is the combination of intravenous BCNU with intra-arterial cisplatin. The trial had also included a third arm in the randomization, used to investigate, successively, new investigational Phase II drugs. The initial agent was 10-EDAM (Edatrexate). When accrual for this group was completed in early 1992, randomization was begun to Piroxantrone. Accrual to this third arm was later terminated early by the Division of Cancer Treatment (who funds the BTCG and is responsible for all official NCI decision-making concerning these trials), because of a decision not to pursue the agent Piroxantrone. Followup continues on all patients on BTCG 89-01, with appropriate data monitoring.